SIST ISO 12646:2010

INTERNATIONAL ISO
STANDARD 12646
Second edition
2008-06-01
Graphic technology — Displays for
colour proofing — Characteristics and
viewing conditions
Technologie graphique — Affichages pour la réalisation d'épreuves en
couleur — Caractéristiques et conditions d'examen visuel

Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions. 1
3.2 Abbreviated terms . 3
4 Requirements . 3
4.1 Resolution . 3
4.2 Size. 3
4.3 Refresh rate (CRTs only). 4
4.4 Uniformity of luminance. 4
4.5 Geometric accuracy (CRTs only) . 4
4.6 Convergence (CRTs only). 4
4.7 Ambient illumination, surroundings and environment. 4
4.8 Chromaticity, luminance of the white and black points, and tracking (channel balance) . 5
4.9 Gamma. 6
4.10 Colorimetric accuracy and grey balance . 6
4.11 Directional variation of luminance and chroma (FPDs only) . 7
5 Test methods. 7
5.1 Preparation and instrument set-up. 7
5.2 Resolution (CRTs only) . 7
5.3 Uniformity . 8
5.4 Geometric accuracy (CRTs only) . 9
5.5 Convergence (CRTs only). 10
5.6 Measurement conditions . 10
Annex A (informative) Characterization and calibration . 14
Bibliography . 18

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12646 was prepared by Technical Committee ISO/TC 130, Graphic technology.
This second edition cancels and replaces the first edition (ISO 12646:2004), which has been extensively
revised to include the particular requirements of flat panel displays.
iv © ISO 2008 – All rights reserved

Introduction
The ability to match colour images displayed on colour monitors to the images produced when the same
digital file is rendered by proofing and printing systems (commonly referred to as “soft” proofing) is
increasingly expected in graphic arts. Obtaining such a match is not simple and to be fully accurate requires
careful control of many aspects of the process. The primary purpose of this International Standard is to make
recommendations with respect to the soft proof viewing conditions. If these are controlled, it is then possible
for users to exchange meaningful calibration (3.1.1) and characterization (3.1.2) data such that a consistent
and, possibly, accurate colour match to the hard copy proof is achieved. In the case of visual display devices,
the RGB device values are related to CIE tristimulus values.
The appearance of a colour image on a colour display is influenced by many physical factors other than
controlled ambient viewing conditions. Among the most important of these are uniformity, convergence, size
and resolution (in order to permit rendition of the proof at close to its normal size and with the finest detail
visible on the hard copy at normal viewing distances), variation of electro-optical properties with viewing
direction, freedom from flicker and glare (specular reflections with distinct images), the opto-electronic
calibration of the display and the settings of its display driver software. So, to be acceptable as a proofing
system which provides a reasonable level of image quality, the display must also exhibit these properties at an
acceptable quality. This International Standard is based on the use of the flat panel display (FPD) and cathode
ray tube display (CRT) technologies. It specifies the requirements for factors such as uniformity, convergence,
refresh rate, size and spatial resolution. However, since these parameters are subject to improvement as
display technology changes, this International Standard only defines minimum requirements for these
parameters. It is assumed that displays used for this purpose will always conform to accepted industry
“standards” for computer-aided design (CAD), and generally provide quality levels considered acceptable for
this purpose, where they offer an improvement over the specifications herein.
Note that, even for displays of the highest quality, the appearance of the displayed image will be limited by the
accuracy of the colour transformation used for converting the digital file from its encoded colour space to that
required for display purposes. This International Standard provides no formal specifications for these
transformations, although the issues are discussed in an informative annex (Annex A), together with
recommendations for achieving an acceptable colour transformation.
This International Standard only considers the setting up of colour displays as “soft” proofing devices. It
primarily focuses on applications where the displayed image will be directly compared to a hard copy.
However, in some practical situations, the image on the screen is evaluated in the absence of a hard copy. In
this International Standard examples of two practical use cases are described. The first concerns the
comparison of a soft proof with a hard copy proof; the second concerns the viewing of displayed images
independently of any hard copy image. For the viewing of displayed images independently of any hard copy
image, less restrictive requirements are sufficient, and they are stated separately in this International Standard.
This viewing is therefore concerned with modifying the “hard” and “soft” controls of the display to enable it to
simulate a proof. In this sense, it can be looked on as a “slave” device. However, it is in the interests of a CAD
user, where the colour display in a real sense “originates” from the image, to set up the display in a similar
way. This will enable simpler optimization of the colour transformation to the selected hard copy system used
for rendering the image, in order to produce an accurate reproduction, if this is an important requirement.
However, it is possible to undertake image processing to modify the image when rendered to make it look like
the displayed image (colour gamuts permitting) whatever the opto-electronic calibration of the display. This is
briefly discussed in Annex A.
[14]
Users of this International Standard will also benefit from CIE Publication 122 . Those unfamiliar with the
[9]
judgement of displays may also find it helpful to read IEC 61223-2-5 which contains much useful detailed
information about evaluation and testing of image display devices.

INTERNATIONAL STANDARD ISO 12646:2008(E)

Graphic technology — Displays for colour proofing —
Characteristics and viewing conditions
1 Scope
This International Standard specifies the minimum requirements for the characteristics of displays to be used
for soft proofing of colour images. Included are requirements for uniformity, convergence, refresh rate, display
diagonal size, spatial resolution and glare of the screen surface. The dependence of colorimetric properties on
the electrical drive signals and viewing direction, especially for flat panel displays, is also specified.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3664, Graphic technology and photography — Viewing conditions
1)
ISO 13655:— , Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ISO 15790, Graphic technology and photography — Certified reference materials for reflection and
transmission metrology — Documentation and procedures for use, including determination of combined
standard uncertainty
CIE Publication 15, Colorimetry
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
calibration
operation of establishing that the measured values agree with the values specified by a standard or a
characterization process
3.1.2
characterization
process of relating device-dependent colour values to device-independent colour values

1) To be published. (Revision of ISO 13655:1996)
3.1.3
convergence
ability of the three electron beams (R, G and B) to come together at a single spot on the surface of the CRT
(see 3.2)
NOTE Not applicable to FPDs (see 3.2).
3.1.4
DVD
design viewing direction
direction for which specific electro-optical characteristics of the display have been optimized
NOTE Examples of important
...